The invention relates to a membrane support system which applies tension to the membrane of a sound producing or sound receiving device, such as a speaker or a microphone, respectively.
The prior art relating to membrane support and tension systems utilize various techniques. The U.S. patents to Selinka U.S. Pat. No. 5,850,461, Carver U.S. Pat. No. 4,803,733, Thigpen U.S. Pat. No. 4,837,838, Torgeson U.S. Pat. No. 4,468,530, and Recklinghausen U.S. Pat. No. 4,037,061 disclose rigidly affixing a loudspeaker membrane to a supporting structure. In other cases, membrane tension is applied by rigidly holding the membrane by the edges and introducing an inelastic deforming protuberance to apply membrane tension. The protuberance is positioned in grooves within the mounting structure. With each of the aforementioned references, the membrane edges are rigidly affixed so that no additional flexure of the membrane material is allowed. Consequently, the tension in the membrane must increase when it moves backward and forward from its center, or rest position. This limits the membrane excursion range, and thus the speaker""s maximum acoustic output and dynamic range.
In the Bruney U.S. Pat. No. 4,939,784, front-to-back excursions of the membrane edges are prevented, and the membrane edges are allowed to move inward, in the plane of the membrane, as the central membrane moves back and forth. In this way, tension variation in the membrane is appreciably reduced and the useable excursion range of the membrane is increased. However, an apparatus for applying tension across the membrane is not disclosed.
The present invention is a membrane support system for applying tension to a membrane that is connected to a frame by incorporating a tensioning device that provides mechanical compliance in the direction of the plane of the membrane. The system includes a frame that has an opening, a membrane that is connected with an exterior surface of the frame and spans the frame opening, and a tensioning device that is connected with the frame for deflecting a portion of the membrane within the opening of the frame. The tensioning device includes a clamping member which is secured to the frame and extends over the frame opening, and a support formed of a compliant material that is connected with the end of the clamping member which extends over the frame opening. The compliant material of the tensioning device allows the membrane to exhibit a high degree of flexure both within and beyond, i.e. normal to, the plane containing the membrane.
According to a further object of the invention, the membrane support system includes a compliant roller which acts as a tensioning member for the membrane. The roller tensions the membrane within the plane thereof and the roller rotates in a plane parallel to the membrane plane during excursions of the membrane to relieve excess tension.